1. Field
The present invention relates to a method, system, and article of manufacture for verifying a record as part of an operation to modify the record.
2. Description of the Related Art
In certain computing environments, multiple host systems may communicate with multiple control units (CUs) (also known as storage controllers, storage subsystems, enterprise storage servers, etc.) providing access to storage devices, such as interconnected hard disk drives through one or more logical paths. The interconnected drives may be configured as a Direct Access Storage Device (DASD), Redundant Array of Independent Disks (RAID), Just a Bunch of Disks (JBOD), etc. The control unit may configure one or more logical subsystems (LSSs), where each LSS is configured to include multiple volumes.
In certain situations, the host systems may want to modify a record managed by the control unit for which a lock must be obtained. As part of modifying the record, the host may issue a search command, through a channel subsystem program in the host, to have the control unit compare the record to modify with the value of the record when the modify operation began to determine whether the value has changed notwithstanding the lock on the record. If the search response indicates that the record value has not changed then the channel subsystem program may proceed to a next channel command word to send to the control unit to execute to modify the locked record or other data object. If the record value has changed, i.e., the record does not match the search value, then this failure may indicate a hardware and/or software problem in the control unit or host. In such case, the channel subsystem program will proceed to an error handling mode and not proceed with the record modification.
There is a need in the art for improved techniques for handling atomic operations.